Plums and Damsons
In recent years there has been a great deal of work done on the root stock of many varieties to promote dwarfing thus making them suitable subjects for the smaller garden and even containers.
They may be grown as fans, for wall-training or with the support of posts and horizontal wires, but root-pruning will probably be necessary every five years or so to restrain growth and maintain fruiting.
Plums do not produce fruiting spurs as apples and pears do, making them less amenable to training, and they are seldom satisfactory as cordons or espaliers.
Week 5 onwards:
Protect the flower buds against bird damage by covering the trees with netting or by spraying with a deterrent.
Week 8 onwards:
Firm any trees that are lifted by frost during the months after planting.
Prune young trees to ensure speedy healing of cuts.
For established trees see note in Week 21.
Spray early flowering trees with a general insecticide.
Apply to the trees as the buds burst and this will control pests such as aphids and caterpillars.
Choose a day when there is no wind and spray drift will not present any problems.
Trees need nitrogen to promote foliage and vigorous growth, phosphorus for healthy growth and fruit and potassium for good fruit-bud development fruit colour and flavour.
How much feeding fruit trees need depends on the soil and can be adjusted depending on growth, cropping and soil analysis.
In most instances apply 100g (4oz) of general-purpose fertilizer, and 20gms (¾ oz) sulphate of potash per sq m.
Ideally keep a grass-free zone at least 1 m wide around the base of the tree/s, this area should be mulched with low-nutrient mulch such as garden compost.
Apply superphosphate every two or three years at 40 - 50 gms per sq. metre (1.5-2 oz/sq yd)
For trees in grass, apply fertilisers in Dec / Jan.
Week 18 :
Watch for drying out early in the first season after planting.
Water trees if necessary.
Alternatively if not done previously, mulch around the tree/s with well-rotted manure to retain moisture.
Hang pheromone traps in trees this month to catch plum and codling moth.
A small plastic cone inside the trap releases the scent of the female to attract male moths, which become stuck on the sticky insert before they've had a chance to mate with females.
If moths can't mate, this results in; 'no eggs and no maggots'.
Replace the cone and insert regularly to keep the trap working effectively.
Plums and related prunus species rarely need pruning.
Some trees may only require light pruning to maintain shape and to keep the centre open.
Timing of pruning is important to avoid silver leaf disease, i.e. only do it around now when the tree is in full leaf.
If there are any badly placed or damaged branches that do require attention, then prune them any time from now until mid-July.
Neglected trees should be thinned out over several years.
If silver leaf infected branches are removed, ensure that they are cut back 100-150mm (4”-6”) behind the point where the inner wood is no longer stained.
Hygiene is paramount, paint any wounds caused by pruning with a wound dressing, and be sure to disinfect pruning tools after working on each tree to prevent transference of disease.
Week 22 - 27:
Thin the crop to 50 - 70mm (2"- 3") apart (slightly more for large fruited varieties) to improve size, colour and flavour.
Week 23 onwards:
Plums are shallow-rooted, and can be harmed by deep cultivation.
Control weeds by shallow hoeing.
If trees are growing in grass, keep it close cut, especially during dry weather.
Remove suckers as they form, pulling them out with as little root disturbance as possible.
Week 26 onwards:
Fit scarers in trees to reduce fruit damage by birds.
Locate jars partially filled with sweetened water in the branches to catch wasps.
Check the sticky card in pheromone traps regularly, and change when they are full.
Gather up windfalls to prevent disease.
Week 30 onwards,
Reduce the risk of silver leaf attack by avoiding branch splitting and breakage caused by heavy crops.
Support individual branches with stakes, wrapping the branch to avoid chafing, or use a post and tie the branches to it.
Leave dessert varieties to ripen on the tree and pick them carefully when ready.
Fruits for jam, bottling or cooking, particularly gages, are best picked before they ripen.
Normally, plums will not store after picking, but some varieties can be kept for two or three weeks in a cool place if picked when under-ripe and wrapped in paper.
Handle exhibition fruits by their stalks to avoid disturbing the surface bloom.
Week 35 onwards:
Plant and support maiden* trees.
(* two or three year-olds if the trees are to be trained)
Plums do best in deep, well-drained heavy loams, and will tolerate slightly acid soils.
Do not bury the union between rootstock and scion, otherwise the variety may form its own root system and the effect of the rootstock will be lost.